Road traffic-control signboards are essential elements in running of vehicles. Since road traffic-control signboards should be optimally recognized at drivers' visual fields, they are usually fixed at right angle to vertical supports which are built vertically at the margin of roads. For example, a conventional road traffic-control signboard assembly will be described below with reference to part of FIG. 1.
In the case of the conventional road traffic-control signboard assembly, a road traffic-control signboard 40 is simply fixed to the road traffic-control signboard stay bar 1 which is extended again over the road, using a U-bolt and nut. Therefore, assemblers' manpower can be reduced but the durability thereof is very poor. The following problems are caused. That is, as stated above, the conventional road traffic-control signboard assembly assembles the road traffic-control signboard 40 with the traffic signboard stay bar 1 using the U-bolt and nut. Thus, if strong force is applied to the conventional road traffic-control signboard assembly, because typhoon blows, an initial position of the road traffic-control signboard 40 is changed to thus make the front surface of the road traffic-control signboard 40 turn up to the sky or down to the road, or make it suspended at a slope. As a result, the road traffic-control signboard 40 loses its function and causes a failure in safety running of vehicles.
In the meantime, if impact is applied to the conventional road traffic-control signboard assembly, due to the excessively loaded freight in freight vehicles or the top portion of special-purpose motor vehicles such as cranes or heavy equipment, the obverse of the road traffic-control signboard 40 is slanted heading toward the road or is damaged. Finally, the same problems as those described above are caused. Hereupon, local government road facilities that receive accident or damage reports ride bucket vehicles and go to sites immediately, in order to straighten the road traffic-control signboard whose initial position has been changed again or replace it by a new one. For this reason, roads are blocked to thus delay a smooth road condition and cause a big economical loss and damage nationalistically. On the other hand, when typhoon blows or after typhoon passes a lot of road traffic-control signboards are out of position over the downtown whole area. In this case, big problems such as confusion, discomfort, and traffic jams are caused.
Moreover, repair works of long hours cause various kinds of big problems. Hereupon, to solve the above-described problems, this inventor filed a Utility-model application No. 20-2003-0040773 on Dec. 26, 2003 with the Korean Intellectual Property Office entitled “Horizontal support structure for making traffic-control signboards rotate” which has been registered as a Utility-model registration No. 20-0349900-0000 on Apr. 29, 2004. By the way, the above-described registered conventional art greatly changes the structure of the existing road traffic-control signboard stay bar 1. In principle, the existing road traffic-control signboard stay bar 1 does not cause any problem but is complicated in the structural viewpoint since a coil spring should be is mounted so as to be concentric with the road traffic-control signboard stay bar 1. As a result, in the case of the conventional art, it is not so easy to manufacture the road traffic-control signboard 40 and assemble it in the road traffic-control signboard stay bar 1 to thus cause the manufacturing cost to greatly rise up and the maintenance to be difficult and to additionally cause an unsafe problem since the weight of the road traffic-control signboard assembly is heavy.